Roasting furnace



A. V. I ,EGGO

ROASTING FURNACE Original Filed Dec. 22. 19:21

l/vvf/VTOR ARN/0R V. 5660,

Feb. 26 1924. 1,484,79l

A. V. LEGGO ROASTING FURNACE Original Filed Dec 22 1921 v l 5Sheets-Sheet 2 'l "13; ARTHURV. Laeeo Patented Feb. 25, i924.

Uhliif SFTES ARTHUR VICTGR LEGGO, OF IEELBOURNE, VICTORA, AUSTRALIA.

ROASTING FUBNACE.

Original application filed December 22, 1321, Serial No. 524,301.

Serial No. 649,382.

To all atomv vit may conce/m.'

Be it known that ARTHUR Vieron Lneeo, of 497 Collins Street7 Melbourne,in the State of Victoria, Commonwealth of Australia, metallurgist7 haveinvented certain new and usefr-.il lmprovements in Roasting Furnaces, ofwhich the following is a specification.

This invention relates to improvements in the rabbling mechanism of oreroasting furnaces and refers especially to the arms and teeth on therabble shafts for stirring and exposing the ore in its passage throughthe furnace. Y

The object of the invention is to provide certain improvements in theconstruction and arrangement of rabble teeth for attachment to a rabblearm whereby a tho-rough stirring and even distribution of the orepassing over the hearth of a furnacel and an eectual exposure of the orebeing stirred to the action of the furnace gases is effected.

l accomplish the abovementioned object by providing the rear of a rabblearm with a row of detachable furrow forming teeth and the front of thearm with a row of stirring teeth having downwardly, forwardly andinwardly inclined narrow shanlrs terminating in broad feet set at anangle to the front of the arm and disposed to travel between the centresof the paths traversed by the furrow forming teeth.

The stirring teeth may be arranged with the front of the foot on thecentre tooth set radially to the pivot point of the arm and with thefeet of the teeth on the inner and the feet of the teeth on the outerparts of the arms set at opposite angles to the radial line whereby thesaid teeth in the act of stirring the ore will ensure the same beingmaintained at a uniform depth over the whole area of the furnace hearth.

ln order that the invention may be readil),7 understood reference willnow be had to the accompanying sheets of explanatory drawings whereinFigure l is a view in sectional elevation of part of a straight linemultiple hearth furnace showing a rabble shaft with arms fitted withteeth constructed in accordance with the present invention.

Figure 2 is a View in elevation of a rabble arm fitted with stirring andfurrow forming teeth constructed and arranged in accordance with thepresent invention. In

Divided and this application filed July 3,

this view the inner end of the rabble arm and part of a rabble shaft areshown in section.

Figure 3 is a view in plan of Figure 2.

Figure -t is a view similar to Figure 3 showing a modified form offurrow forming tooth attached to the rear of the rabble arm.

Figure 5 is a view similar to Figures 3 and 4 showing combined stirringand rabbling teeth attached to the arm.

Figure 6 is a view in perspective of the outer end of a rabble armfitted with stirring and furrow forming teeth and drawn to a largerscale than the other figures.

Figure 7 is a View in perspective of an oblique furrow forming tooth forattachment to the rear of the rabble arm.

Figure 8 is a view in perspective of a modified form of stirring toothfor attachment to the front of a rabble arm.

Figure 9 is a View in end elevation of a rabble arm showing a combinedstirring and furrow forming tooth attached thereto'.

Figure l0 is a view similar to Figure 9 and showsl a slight modificationin the construction o-f the combined stirring and furrow forming tooth.

In these drawings the numeral 13 designates a rabble shaft having rabblearms 36 projecting alternately from opposite sides thereof.

rlhe rabble arms are formed with longitudinally disposed flanges 82 and83 which project horizontally from both sides thereof and on the upperside of the leading flanges 82 and on the underside of the followingflanges 83 are formed a plurality of tapered projections 84.

A plurality of stirring teeth 85 and a plurality of furrow forming teeth86 are detachably secured to the flanges on the rabble arms by taperingjaws 87 which are adapted to be passed over the flanges and movedlaterally thereon to engage with the tapered projections 84, and thesaid teeth van be locked securely on said flanges by means of lockingbars 88 or other approved devices in the ordinary way.

Part only of a locking bar 88 is illustrated in Figure 6 of the drawingsand it is shown ready to be dropped into position so that projections onthe underside thereof will prevent the jaws of the teeth moving inwardoff the tapered projections 84.

`When the rabble teeth are aflixed to the V82 of the arms are formedwith narrow shanks 89 which incline forwardly, inwardly and downwardlyand terminate in broad feet 90 having bevelled lower edges (sce l 1igure 6).

The upper surfaces of the broad feet oif the stirring teet-h are madehorizontal as shown in Figure 27 or they can be thickened on one sidesok as to give them a suitable lateral inclination (see Figure S) ineither direction `to cause the ore to be moved inward or outward asdesired during the stir n ring operation.. The inclination of the feeton the teeth (shown in Figure S) is arranged to cause the ore beingrabbled to be moved outwardly and it will obvious that when an oppositeinclination is given to the feet the ore will be moved inwardly.

The shanks 89 of the front teeth are inclined inwardly so as to lie moreor less in line with the centre of the paths of movement of their lowerends when the arm is in operation.

All the front teeth. S5 with the exception of the innermost one are madeuniform in size and shape and owing to the set of the slianks the frontedges of the feet thereon are'disnosed at an an le to the front of thellabble arm. rlhe front of the feet on the teeth near the centre of therow is disposed in or approximately in a radial line (marked A in Figure3) drawn from the centre of the rabble shaft and the front of the footci' the outermost tooth is so arranged that its outer side is in advanceof the inner'side as clearly indicated by a radial line (marked B inFigure drawn from the centre of the rabble'shaft through the inner sideof the said foot. rThe front of the foot 'on the innermost tooth isarranged so that its inner side is in advance of its outer side and maybe in the same radial line (marked (l inV Figure 3) to that passingthrough the outer side of the leading edge of the neXt ad]a cent tooth.

ln most rabbling operations where rotatre there I employed to pass orcver the hearth is a tendency for the ore to be distrilaited more or lossunerenlwr and with a greater depth toward the outer part of the pathstraversed by the said arms, and for the dead oro on the hearth to beleft exposed to the furnace gases atY the Ybottoni of the furrows formedby the lteeth. li/lany ores are likely to form cakes when leftundisturbed and exposed to the furnace gases and more especially thoseores containing zinc and lead. VThe construction and arrangement 'of thefront teeth as above de' scribed tends to obviate the unevendistribution of the ore ast-he angles of the feet of thel outer teethserve to counteract such tendenclos, and to keep a complete covering ofrabbled ore evenly disposed over the bed so as to prevent the exposureof the unrabbled ore to the gases and so retard or prevent the dead oreforming into hard cakes. T he setV of the feet of the inner front teethserves lto move outwardly any ore which may mount up adjacent to therabble shaft and thereby prevents the said ore passing'down the sleeve91 surroundingthe shaft, to the hearth beneath.

'.ll e feet 90 of the teethinay beY made sufficiently broad to ensurethe sides of each tooth traversing a path which meets with o crei-lapsthe path traversed by the nearest si of the adjacent teeth as vshown bythe concentric dotted lines 9:2 in Figure 3 of the drawings rlhe outerside of each front tooth is disposed in advance of the inner K side ofthe next outermostL toothV thereby leaving' openings 85" through whichthe ore passesV radially between the feetwhen the rabbling mechanism isin operation' thus facilitating thc passage of the teeth through theore. Y

The construction and set of the lfront teeth arefsuch that theyVthoroughly stir the whole bed of ore well in advance of the rabble armwithout causing it to Abank up unduly with the result that the load onthe arm is kept smaller and the'teeth attachments kept cooler than whenit is banked the ore so'as to ensure a fresh surface be-A ing exposedYandthe back teeth S6 (which are made shorter than the front teeth) leavethe surface ot the ore toi-med into deep furrows and ridges therebycausing'a maximum of surface to beV exposed.Y @n the next revolution ol"the arm the Shanks 89V of the front teeth pass through'the ridges Y leftbetween the .furrows and distribute the ore laterally sc that the bed ofore is flattened more or less before the oncoming rear teeth 86 againform it into furrowsf ln the present invention the j teeth are designedespecially'V to' keep Vthe ore evenly distributed over the hearth of thefurnace' and prevent any unrabbled ore from being exposed to the furnacegases at the bottom of the furrowsy formed by the back teeth.V

As the bottoni of the back teeth is higher than the bottoni of the frontteeth it will be apparent that no exposure of unrabbled ore on thehearth can taire place which might cause a calring or setting of thesaine.

The inner ends of the rabble arms are fitted with broad obliquelydisposed teeth 93 which operate to inove the ore away from the rabbleshaft and prevent the sa 'l ore banking up suiliciently to jews 'do-.mthe sleeve surrounding the said shaft and falling to the hearththerebeneath.

The angle of the inner strirring teeth on each arin is greater than thatef the remaining stirring teeth with the result that they act to throwfurther outward the ore pushed baclr by the action of the oblique teethand thereby effect a incre even distribution of the ore on the hearth.

The furrowY forming teeth 86 on the following flange 83 to traclr midwaybetween the shanlrs of the front teeth and depend from the saidfollowing flange as shown in Figures 2 to 6 of the drawings.

rlhe faces of the rear teeth 86 for forining furrows and ridges in theore are flat and may be set in line with the edge of the followingflange as shown at D in Figure 6 or seine or all of the teeth rnay beset obliquely to the said flange as shown in Figures 3 to 5 and on theouter end of the arni shown in Figure 6 as desired. wiWhen the teeth S6are set obliquely seine of theni can be arranged to move the oreradially in one direction and the remaining or some of the remainingteeth can be arranged to inove the ore radially in the oppositedirection (see Figure e). The rear teeth can all be arranged at thesarne angle as shown in Figure 3 or some of the teeth can be i'orinedwith more or with less obliqueness than the others as desired.

'lhe arrangenient of the rear teeth as above described enables the orebeing rabbled to be passed over a hearth in any direction at a desiredrate of speed whilst keeping the sa ne at a more or less uniform depththroughout all parts of the hearth.

ln lieu of securing the stirring and furrow forming teeth detachably tothe rabble arins either cr both can be cast integrally on the front andrear thereof and be Otherwise constructed and arranged as abovedescribed.

ln an alternate construction (see Figures E) and l0) the stirring andfurrow forming teeth are formed integrally with each other and thefurrow forming teeth are set obliquely to the axis of the arm7 and asshown in Figures 5 and l0 the furrow forming teeth can be formed ofgreater breadth than the furrow forining teeth illustrated in the etherfigures of the drawings.

The combined stirring and furrow forniing teeth are formed with two jawswhich engage both flanges of the rabble arins and the teeth are retainedin correct spaced relationship by ineans of distance pieces 95 forinedon the sides thereof and which abut against each other when the teethare thrustover the ends of the arms and inte position thereon. yTheObliquity and shape of the furrow forining teeth are shown in dottedlines in Figure 5 and this forni of furrow forming tooth is particularlyadapted to facilitate the movement of the ore over the hearths of turretfurnaces.

l claini:

l. ln roasting furnaces. rabble arin7 a row of stirring teeth on thefront and a row of furrow forming teeth on the baclr of the rabblearin., and dowr ii'dly., ferwardly and inwardly inclined slianlis onthe. stirring teeth having broad feet set an angle to the front of therabble arn'i.

2. ln roasting furnaces, the combination with a rabble arni of a row offurrow forni-- ing teeth on the rear of the arin,l row cf stirring teethon the front of the arn'i having narrow downwardly, forwardly, andinwardly inclined shanlis adapted to pass through the ridges of orebetween the furrow formed by the rear teeth, and broad feet on thestirring teeth having their front faces set at an angle to the front ofthe arni whereby when the arin is in inotion the paths of the stirringteeth overlap and the ore being stirred will pass radially between thesides of the feet and between the front of one stirring tooth and theback of the neXt adjacent stirring tooth.

3. ln roasting furnaces, the combination with a rabble arin of a row offurrow forniing teeth on the rear of the arin, a row of stirring teethon the front of the arm having downwardly, forwardly and inwardlyinclined shanlrs, broad feet on the stirring teeth set at an angle tothe front of the arin, the front of the foot of the centre stirringtooth being set approximately radially to the pivot point of the arin,and the feet of the teeth on the inner and the feet of the teeth on theouter parts of the arm being set at opposite angles to the radius oftheir path whereby the said teeth in the act of stirring thc ore willensure the saine being maintained at a uiforin depth over the whole ofthe furnace hearth substantially as described.

4. ln roasting furnaces, a rabble arin having a row of stirring teeth onthe front the-reof. and a row of furrow forining teeth depending frointhe arni at the rear of the stirring teeth and having oblique facesarranged to niove the ore being rabbled in a radial direction.

5. ln roasting furnaces7 a rabble arni having a row of stirring teeth onthe front thereofT and a row of furrow forming teeth on the rear of thearm, seine of the said furrow forn'iing teeth having iiaces setebliqnely to the arm and the remaining furrow torming teeth having facesset in line with the sait arm.

6. In roasting furnaces, a rabble arm having stirring teeth on the frontthereof provided with depending` narrow Shanks having broad shallow feetadapted to cover the whole path of the rabble, and furrow forming teethen the rear of the arm having their lower ends disposed above the levelot the i'eet on the stirring teeth.

7. In roasting furnacese a rahble arnn having a row of teeth on the fearand a row of teeth on the front thereof, tapered projections on thefront Yand rear ot' the arm, jaws on the upper ents et the front teethengaging the projections en the :trent of the arm, narrow Shanksinclining inwardly, 'torwardly and downwardly from the said aws, broadfeet on the lowerl parts of the said shanks set at an angle to the frontof the rabble arm and adapted to track so that the sides et the pathtraversed by the edges of each tooth will overlap the paths ot theadjacent teeth on the arni. y

8. In roasting furnacesy a rabble arnn a row of stirring teeth on thefront and a row offulrow forming teeth on the rear of the arm7 saidstirring teeth having forwardly` and' inwardly inclining shanks7 broadfeet on the Shanks having horiZent-al lov-Jer surfaces andinclined'npper surfaces whereby when the rabble is in action theinclination of the upper surfaces oi the said broad feet Vwill move theore laterally.

9. In rabbling inechanisn'i of roasting ur- Y nace a rabhle'arm havingcombined stirring n ring and furrow orn'iing teeth comprising narrowforwardly, downwardly and inwardly inclining shanks having a broadiootat their lower ends obliquely disposed blades at the rear ot the Shankssaid obliquely disposed blades being arranged to track at one side ofthe paths taken Vby the feet on theinclined shanks and having theirlower ends above the bottoni oit the said feet, and means for attachingthe combinedteeth to the ble arm.

ln testimony whereof l haveV alixedA my signature.

ARTHUR vieron Lneefo

